SF South Bay to Capitola (Over 1800ft Summit) Trip Data

[JoeS]

SF Peninsula --> Capitola and Back Over Hwy. 17 1800ft. Summit

Trip from my house (Los Altos Hills) to Capitola was 41.2 miles. I started with 16 bars and RR of 94 and arrived in Capitola with 9 bars and RR of 49. Temperature a little under 70degF. No heat or aircon, but driving lights on (not headlights).

Fully recharged in Capitola.

Returned home, starting in Capitola with 16 bars and RR of 93 and arrived at home with 5 bars and RR of 20 for a trip distance of 40.8 miles (slightly different route). Temperature around 50degF and headlights on. No heat or aircon.

I recorded data points going but inadvertently disabled my recorder coming back. Graph below is for the trip going out.

I drove conservatively on the way to Capitola, and the uphill drive was slowed by construction and a 40mph speed limit. This made a significant contribution to extending the range. On the way back, I was much less conservative.

Regeneration on the long downhills not only resulted in my RR increasing but the fuel gauge bars also increased (by one bar) a few times.

Another observation - I'm beginning to wonder if our Fuel Gauge is linear; i.e., the first eight bars drop slower than the last eight bars. Don't have enough data to support or refute this, but it's something worth keeping an eye on...

ASSESSMENT

In an earlier post I allowed as I thought the typical high-speed highway range upper limit is around 50 miles, and I'll stick with that for planning purposes; however, the iMiEV is really responsive to gentler and slower driving and I'm sure a range of 80 miles is readily achievable on lower-speed roads. The good news here is that if there is any concern at all of being able to get to a destination, then simply slowing down and picking a gentler route will dramatically improve the situation. Heck, if I believed the instrumentation, it told me that on the outbound trip, after covering 41.2 miles I still had a RR of 49 miles... then I'd have been able to have gone over 90 miles.

EV drivers don't have range anxiety because we have a very good handle on what our range is! :!: That's why all this data-taking at the outset.

For ourselves, now that we've tested and taken enough data to be comfortable, we're going to be quite content keeping our fuel gauge between six and fourteen bars for our everyday driving, content in knowing just how far we can push it if we have to.

Edit 11/2/16
OMG, I didn't realize that the PDF doesn't show up as an image.
(Apple's Safari shows it whereas Google's Chrome doesn't)
Here's the link: http://www.katiekat.net/Vehicles/Mitsi/MitsiCapitolaTripGraph.pdf

Edit 4/30/17
Added the GPS Visualizer graph of this trip:

 

[FiddlerJohn]

... after covering 41.2 miles I still had a RR of 49 miles... then I'd have been able to have gone over 90 miles.

http://www.katiekat.net/Vehicles/Mitsi/MitsiCapitolaTripGraph.pdf

The RR was using your recent history of driving down hill. I can see the two places on your graph where you said the bars when up because of regen. Than would make the RR optimistic unless you could continue down hill (at the same rate below sea level) for the next 49 miles..

Since the i has 16 kWh of battery and 16 bars, I use a 1 kWh per bar approximation. I think that is a good first order approximate except the bottom first bar which seems to have more energy that than the others.

Great Graphs. Thanks

 

[JoeS]

... would make the RR optimistic unless you could continue down hill (at the same rate below sea level) for the next 49 miles..

Guess I used the wrong smilie (smily?) for the tongue-in-cheek 90-mile comment. Next time I'll use:

Actually, based on what little I've measured so far, I'm sure I could easily exceed 100 miles with the iMiEV if I were allowed to dictate the conditions :roll:

 

[jray3]

You go Joe! What sort of datalogging equipment are you using. I've been meaning to make a serious effort at the Speedbox app, which logs speed and altitude, and put a CT around the motor input for logging amps.

 

[JoeS]

jray3 -

My datalogging is an old-fashioned small hadheld voice recorder (it even uses tape!) that I periodically read off my Garmin GPS and instrument panel. I'll take one of my handheld GPS' next time (or maybe the iPad with GPSMotionX) in order to record altitude, as that's a significant piece of our puzzle.

I've got a nice CT with 12v-driven display, but it can handle wire only up to about 1/2" dia. Where would you attach it? What I'm really curious about is the magnitude of regeneration as shown on the iMiEV display compared to what the other side of the display shows when accelerating.

After running these tests I'm pretty confident to have sussed-out the iMiEV's limits and can now just settle down and use it as a daily driver - besides, my wife is back (she was gone last week while I was doing all that testing) so I have to stop playing with HER car. :roll:

 

[Pier]

Joes wrote : « Another observation - I'm beginning to wonder if our Fuel Gauge is linear; i.e., the first eight bars drop slower than the last eight bars. »

I did a test early this morning concerning the linearity of the bars. This is part of a long very slow 3 days trip to see how many km I can do (Range) on a charge. Up to now I am at 160 km (100miles) with 2.5 bars to go. I won't make 200 km unless I ride really cautiously and slow.

Back to linearity.... I am now sure it is not linear. I did this test over 2 days at the same low speed.

First day very hot 30°C, strong wind

Seg 1 : Bars 15-14-13 average 14.16 km / bar, head wind.
Seg 2 : Bars 12-11-10 average 12.2 km / bar, tail wind.

Second day , 22°C, no wind.

Seg 3 : Bars 8-7-6 average 10.86 km / bar.
Seg 4 : Bars 5-4-3 average 11.86 km / bar.

See segment 2 should have been better with tail wind, and segment 3-4 are even worse with no wind.

Pier

 

[Don]

For ourselves, now that we've tested and taken enough data to be comfortable, we're going to be quite content keeping our fuel gauge between six and fourteen bars for our everyday driving, content in knowing just how far we can push it if we have to.

We came to that conclusion 3 or 4 months ago

Even when leaving on a fairly lengthy trip of 40 or 50 miles, we no longer fully recharge because we're confident we can get where we want to go and back without needing a full pack to do so

We've taken to recharging it a little each time we return home - I check the RR when I shut it off, plug it into L1 and set the kitchen timer for 3 or 4 hours (whatever I think it needs to get it to 11 or 12 bars or so) and unplug it when the timer goes off

Over the past 6 weeks or so, the only 100% recharges have been when we failed to hear the timer go off :lol:

I really wish we had some computerized recharging options where it would automatically shut off at 75% or 85%, but doing it manually isn't all that much trouble and from what I've read on the car and feeding of lithiums, it should really be worth it in the long run

Don

 

[JoeS]

Pier, thank you for your observations. You're right, Seg 1 should have been much lower due to the headwind.

I wrote my comment regarding Fuel Gauge linearity a year ago, and since then have had time to observe…

When charging the iMiEV, the bars DO go up linearly except that the power stays on for an extra hour or so at 16 bars for the final cell balancing. That linearity for a constant (measured) power input is a big clue.

Discharging is SO dependent on external variables that I think it is impossible to make a conclusive statement. The simple fact that you had a varying windspeed alone would throw that out because it is an uncontrolled variable, no matter how perfectly you kept your go-pedal position and carspeed.

Just look at how extremely difficult it is to judge the red needle position when maintaining a constant speed - see this thread:
Speed vs. Power Gauge: Request for Data

Even slight undulations in the roadway mess up that datataking.

When the fuel gauge starts getting low, I can't help think that the fact that we are paying closer attention to it makes it seem that the gauge is dropping faster. :roll:

No, after 17,000 miles of driving the iMiEV, I now think (no proof) that the Fuel Gauge is indeed a linear SOC indicator. I just wish it were a number and not a bunch of bars, but I do appreciate the coincidence that the sixteen bars roughly correspond to our 16kWh battery capacity.

 

[JoeS]

Simply providing a link which shows the data for this trip and discusses miles/bar when climbing (so I can find this in the future):
http://myimiev.com/forum/viewtopic.php?p=30847#p30847